Planets Rapidly Create Holes in Young Circumstellar Disks

Recent spectral observations by the Spitzer Space Telescope reveal that some disks around young (~a few times 10⁶ yr old) stars have remarkably sharp transitions to a low-density inner region in which much of the material has been cleared away. It has been recognized that the most plausible mechanism for the sharp transition at a specific radius is the gravitational influence of a massive planet. This raises the question of whether the planet can also account for the hole extending all the way to the star. Using high-resolution numerical simulations, we show that Jupiter-mass planets drive spiral waves that create holes on timescales ~10 times shorter than viscous or planet migration times. We find that the theory of spiral wave-driven accretion in viscous flows by Takeuchi et al. can be used to provide a consistent interpretation of the simulations. In addition, although the hole surface densities are low, they are finite, allowing mass accretion toward the star. Our results therefore imply that massive planets can form extended, sharply bounded spectral holes that can still accommodate substantial mass accretion rates. The results also imply that holes are more likely than gaps for Jupiter-mass planets around solar-mass stars.